"As the world becomes increasingly connected, their decision to be virtually isolated is very much going to affect their physical world," Schmidt told reporters Thursday at the Beijing airport after the visit to the North Korean capital, Pyongyang. "The government has to do something -- they have to make it possible for people to use the Internet, which the government in North Korea has not yet done. It is time now for them to start or they will remain behind."

Richardson said North Korea is anxious to improve relations with the U.S. and is encouraged by recent statements by South Korea's president-elect, Park Geun Hye. During her campaign, Park said she would be willing to meet with leader Kim Jong Un.

The four-day visit by Richardson and Schmidt was opposed by the Obama administration, which is seeking additional United Nations sanctions to censure North Korea for its long-range rocket launch last month. Opposition from China, North Korea's biggest ally and trade partner, has stalled progress on punishing Kim's regime for violating a UN ban on testing ballistic missile technology.

Richardson's delegation didn't meet Kim and failed to win the release of a detained American citizen. North Korea confirmed last month it had detained the Korean-American after he entered the country in November on a tour. The man, identified as Pae Jun Ho, confessed to committing a crime against North Korea after entering Nov. 3, the official Korean Central News Agency reported, without specifying the crime.

INFORMATION BAN

North Korea bans any infiltration of independent information. Kim, the Swiss-educated leader who is in his second year in power, has increasingly called for greater openness toward using modern technologies such as the Internet. Yet few of the country's 24 million people can access the World Wide Web, and the government offers a domestic intranet service that features an information portal called Naenara.

Schmidt said that North Korea's existing mobile-phone network, operated in a joint venture with Orascom Telecom Media & Technology Holding SAE, could be retooled to offer Internet access. There are about 1 million phones on the network, Schmidt said.

Get The 1600 newsletter

Get our inside look at the White House and goings on in the Donald Trump administration.

Orascom Telecom, an Egyptian mobile-phone operator headed by billionaire Naguib Sawiris, won the exclusive 25-year license in January 2008 for a 75 percent stake in CHEO Technology, a joint venture with the country's state-owned Korea Post and Telecommunications Corp. The Cairo-based company said in February 2012 that subscribers to its 3G mobile-phone network exceeded 1 million.